The term "noncoordinating anion" is now accepted terminology in the field of olefin polymerization, both by coordination or insertion polymerization and carbocationic polymerization. See U.S. Pat. Nos. 5,198,401 and 5,278,119 for early work, and Baird, Michael C., et al, .eta..sup.5 -C.sub.5 Me.sub.5 TiMe.sub.3 B(C.sub.6 F.sub.5).sub.3 : A Carbocationic Olefin Polymerization Initiator Masquerading as a Ziegler-Natta Catalyst, J. Am. Chem. Soc. 1994, 116, 6435-6436. The noncoordinating anions are described to function as electronic stabilizing cocatalysts, or counterions, for cationic transition metal complexes which are active for olefin polymerization as illustrated in the above references among many others. The terms as used here and in the references applies both to truly noncoordinating anions and weakly coordinating anions that are not so strongly coordinated to the cationic complex so as to be labile to replacement by olefinically or acetylenically unsaturated monomers at the insertion site.
U.S. Pat. No. 5,198,401 describes a preferred noncoordinating anion tetra(pentaflourophenyl) boron, [B(pfp).sub.4 ].sup.- or [B(C.sub.6 F.sub.5).sub.4 ].sup.-, wherein the perfluorinated phenyl ligands on the boron makes the counterion labile and stable to potential adverse reactions with the metal cation complexes. Other aryl radicals are said to be suitable in addition to the phenyl radicals, napthyl and anthracenyl are listed. U.S. Pat. No. 5,296,433 teaches the utility of borane complexes comprising tris(pentafluorophenyl)borane and specific complexing compounds. These complexes are said to allow higher molecular weight polymers when used with metallocenes for olefin polymerizaton due to increased solubility of the complexes in monomer or monomer solutions. WO 97/29845 describes the preparation of the organo-Lewis acid perfluorobiphenylborane, and its use to prepare and stabilize active, olefin polymerization catalysts. These cocatalysts are described as being less coordinating than tris(perfluorophenyl)boron, B(C.sub.6 F.sub.5).sub.3, and thus capable of providing higher catalytic activities. Generic description of the suitable cocatalysts according to the application include those of the formula BR'R" where B is boron with R' and R" representing at least one and maybe more fluorinated biphenyls or other polycyclic groups, such as napthyl, anthryl or fluorenyl.